Remove using namespace std;

For historical reasons we had a "using namespace std;" in port.h. This
is generally a bad idea. So removing it and along the way doing a bunch
of cpplint cleanup.

Change-Id: Ia125601a55ae62695e247fb0250df4c6f86c46c6
diff --git a/internal/ceres/low_rank_inverse_hessian.cc b/internal/ceres/low_rank_inverse_hessian.cc
index 4816e3c..3a20c9b 100644
--- a/internal/ceres/low_rank_inverse_hessian.cc
+++ b/internal/ceres/low_rank_inverse_hessian.cc
@@ -37,6 +37,8 @@
 namespace ceres {
 namespace internal {
 
+using std::list;
+
 // The (L)BFGS algorithm explicitly requires that the secant equation:
 //
 //   B_{k+1} * s_k = y_k
@@ -126,7 +128,7 @@
   const int num_corrections = indices_.size();
   Vector alpha(num_corrections);
 
-  for (std::list<int>::const_reverse_iterator it = indices_.rbegin();
+  for (list<int>::const_reverse_iterator it = indices_.rbegin();
        it != indices_.rend();
        ++it) {
     const double alpha_i = delta_x_history_.col(*it).dot(search_direction) /
@@ -173,7 +175,7 @@
             << "approximation.";
   }
 
-  for (std::list<int>::const_iterator it = indices_.begin();
+  for (list<int>::const_iterator it = indices_.begin();
        it != indices_.end();
        ++it) {
     const double beta = delta_gradient_history_.col(*it).dot(search_direction) /